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The technology of hot expanding seamless tube
- Apr 09, 2018 -

Expanding seamless pipe is a kind of hydraulic pressure or mechanical way to increase the expansion of the seamless steel tube along the radial direction from the internal force of the steel seamless tube. Mechanical mode is simpler and more efficient than hydraulic method. In the world, the most advanced large diameter seamless pipe line expansion process is adopted.

The mechanical expansion uses the split fan block in the end of the expander to expand along the radial direction, so that the seamless pipe billet is stepped in the length direction, and the plastic deformation process of the whole tube is realized by subsection. It is divided into 5 stages

1. Preliminary round stage. The fan block opens until all the fan-shaped blocks are exposed to the inner wall of the steel seamless tube. At this time, the radius of each point in the seamless pipe inside the pipe is almost identical, and the steel seamless pipe is initially round.

2. Nominal inner diameter stage. The sector block starts to reduce the movement speed until it reaches the required position, which is the circumferential position of the finished product in the quality requirement.

3. Phase of resilience compensation. The fan block begins at the 2 stage to further lower the speed until the desired position is reached, which is the position of the circumferential position of the steel seamless tube before the process design is required.

4. Stable pressure stabilization stage. The sector position of the sector block remains unchanged for a period of time before the rebound, which is the stage of maintaining the pressure and stability of the equipment and expanding process.

5. Regression stage of unloading. The fan block quickly retracts from the circumferential position of the steel seamless tube before the rebound, until the initial expansion is reached. This is the minimum shrinkage diameter of the sector block required by the expansion process.

In practical application, the 2 and 3 steps can be combined simplified in process simplification, which has no effect on the expanding quality of steel seamless tube.